diff --git a/gallery_dl/extractor/sankaku.py b/gallery_dl/extractor/sankaku.py
index 7db81723..d5309dcd 100644
--- a/gallery_dl/extractor/sankaku.py
+++ b/gallery_dl/extractor/sankaku.py
@@ -76,14 +76,15 @@ class SankakuExtractor(BooruExtractor):
 
     def _tags(self, post, page):
         tags = collections.defaultdict(list)
-        types = self.TAG_TYPES
         for tag in post["tags"]:
             name = tag["name"]
             if name:
-                tags[types[tag["type"]]].append(name.lower().replace(" ", "_"))
-        for key, value in tags.items():
-            post["tags_" + key] = value
-            post["tag_string_" + key] = " ".join(value)
+                tags[tag["type"]].append(name.lower().replace(" ", "_"))
+        types = self.TAG_TYPES
+        for type, values in tags.items():
+            name = types[type]
+            post["tags_" + name] = values
+            post["tag_string_" + name] = " ".join(values)
 
     def _notes(self, post, page):
         if post.get("has_notes"):